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Effect of cavitation on the corrosion behavior of Ti(CN)/TiNb(CN) multilayer in seawater

Abstract:

The superficial wear generated by cavitation in an electrolyte as sodium chloride 3.5%, causes damage in steels AISI 4140 by corrosion, it is commonly used in hydraulic machines, therefore suggest to coat with a Ti(CN)/TiNb(CN) multilayer system deposited with a 200 bilayers period, by means of the technique of physical vapor deposition. The combined action of corrosion and cavitation attacks are monitored by the adequacy of an equipment that consists in ultrasonic oscillator, compound by an oscillating ultrasonic transducer that oscillate at 20 kHz with an amplitude of 100um, and conditioned to a galvanostat-potensiostat. The electrochemical characterization was performed by the electrochemical impedance spectroscopy (EIS) and Tafel polarization curves. As for the results, the hard coating of [TiCN/TiNbCN]n, presented a better resistance to the cavitation corrosion in comparison with the substrate owing to in the steels AISI 4140, the cavitation removes the products of corrosion, accelerating the corrosion rate and decreasing the polarization resistance, in contrast to the obtained in the thin films. © 2014 The Authors. Published by ESG.